This application is based on Japanese Patent Application 2000-54582 filed on Feb. 29, 2000, the entire contents of which are incorporated herein by reference.
a) Field of the Invention
The present invention relates to a timing signal generating device for generating a plurality of kinds of timing signals to drive a solid-state image pickup device including a large number of photoelectric converter elements arranged in a matrix shape and a method of generating the plurality of kinds of timing signals.
The present invention further relates to an electronic apparatus including an electronic device driven by a plurality of kinds of timing signals, the apparatus controlling generation of the timing signals using predetermined data.
b) Description of the Related Art
After the technique to mass-produce charge-coupled devices (CCDs) was established, apparatus such as video cameras, digital cameras, and the like using solid-state image pickup devices of CCD type as area image sensors are rapidly prevailing.
On the other hand, with development of personal digital assistants, a solid-state image pickup device of metal oxide semiconductor (MOS) type consuming less power than the CCD-type solid-state image pickup device is also being developed.
Each of the CCD-type and MOS-type solid-state image pickup devices for an area image sensor includes a large number of photoelectric converter elements. As the photoelectric converter element, a photo diode is used in many cases.
In this specification, xe2x80x9ca large number of photoelectric converter elements arranged in a matrix formxe2x80x9d implies not only xe2x80x9ca large number of photoelectric converter elements arranged in a square matrix form (including a matrix in which the number of rows is not equal to the number of columns)xe2x80x9d but also xe2x80x9ca large number of photoelectric converter elements arranged in a shifted-pixel layoutxe2x80x9d.
In the shifted-pixel layout including a large number of photoelectric converter elements, the photoelectric converter elements in the odd photoelectric converter element columns are respectively shifted relative to those in the even photoelectric converter element columns by about one half of a pitch P1 of photoelectric converter elements in each photoelectric converter element column in a direction of the column. The photoelectric converter elements in the odd photoelectric converter element rows are respectively shifted relative to those in the even photoelectric converter element rows by about one half of a pitch P2 of photoelectric converter elements in each photoelectric converter element row in a direction of the row. Each photoelectric converter element row includes photoelectric converter elements of only odd or even photoelectric converter element columns. The pitches P1 and P2 may be equal or unequal to each other.
xe2x80x9cAbout one half of the pitch P1xe2x80x9d includes, in addition to P1/2, any value which is different from P1/2 because of factors such as a manufacturing error and a rounding error of a pixel position appearing in a design phase or a mask fabrication process and which nevertheless can be regarded as substantially equivalent to P1/2 in consideration of obtained performance of the solid-state image pickup device and picture quality thereof. This also applies to xe2x80x9cabout one half of the pitch P2xe2x80x9d in this specification.
To obtain image data by a solid-state image pickup device including a large number of photoelectric converter elements in a matrix shape, a plurality of kinds of timing signals are required to appropriately drive various constituent elements disposed in the solid-state image pickup device.
For example, a CCD-type solid-state image pickup device requires such timing signals as driving pulses to drive vertical transfer CCDs (VCCDs), driving pulses to drive a horizontal transfer CCD (HCCD), and horizontal synchronizing pulses. Depending on performance of the solid-state image pickup device or performance of the apparatus using the solid-state image pickup device, overflow drain pulses for electronic shutters, clamp pulses for optical black signals, and the like are required.
Of the timing signals necessary for driving the solid-state image pickup device, the HCCD drive pulses, the horizontal sync pulses, the clamp pulses for optical black signals, the overflow drain pulses for electronic shutters and the like have fundamentally a repetition period of one horizontal scan period. Each of these timing signals has a constant pulse waveform in each horizontal scan period. However, the overflow drain pulse and the like are not always used with a repetition period of one horizontal scan period. The overflow drain pulse is not used under a certain operation mode or the like of the solid-state image pickup device. The number and the pulse waveform of each VCCD drive pulses or the like in one horizontal scan period are not fixed.
In this specification, each of the timing signals fundamentally used with a repetition period of one horizontal scan period to drive the solid-state image pickup device and has a constant pulse waveform is called xe2x80x9cclass 1 timing signalxe2x80x9d depending on cases. The class 1 timing signals include the HCCD drive pulses, the horizontal sync pulses, the clamp pulses for optical black signals, and the overflow drain pulses for electronic shutters.
Each of the timing signals generated in horizontal scan periods to drive the solid-state image pickup device and the number of pulses or the pulse waveform thereof in one horizontal scan period is not fixed is called xe2x80x9cclass 2 timing signalxe2x80x9d depending on cases. The class 2 timing signals include the VCCD drive pulses.
A timing signal generating device to generate class 1 and class 2 timing signals is disposed in or outside the solid-state image pickup device. The timing signal generating device includes a storage and a timing signal generator.
The storage stores data defining the class 1 and class 2 timing signals. The storage also stores data to control generation of each of the class 1 and class 2 timing signals in a unit of one horizontal scan period.
In this specification, data defining class 1 timing signals is called xe2x80x9cclass 1 timing signal generating dataxe2x80x9d and data defining class 2 timing signals is called xe2x80x9cclass 2 timing signal generating dataxe2x80x9d. Data to control generation of each of the class 1 and class 2 timing signals in a unit of one horizontal scan period is called xe2x80x9csignal generation control dataxe2x80x9d. The class 1 timing signal generating data, the class 2 timing signal generating data, and the signal generation control data are collectively called xe2x80x9ctiming signal generating dataxe2x80x9d in some cases.
The timing signal generating device generates, according to the timing signal generating data, each of the class 1 and class 2 timing signals at a predetermined point of time respectively.
The signal generating point of time and the signal waveform of each of the class 1 and class 2 timing signals vary depending on the number of pixels, the drive method, and the like of the solid-state image pickup device. The number of pixels, the drive method, and the like of the solid-state image pickup device generally vary according to specifications of an apparatus using the solid-state image pickup device as an area image sensor.
Heretofore, each time specifications of an apparatus using a solid-state image pickup device as an area image sensor is determined, hardware of a timing signal generating device for the solid-state image pickup device is designed and is fabricated.
Even for a slight change of the hardware, the designing and fabrication of the timing signal generating device require a great expense and a long period of development and hence resultantly raises the price of the product. Due to delay in delivery of the product, a business change may be missed in same cases.
It is therefore an object of the present invention to provide a timing signal generating device in which generating points of time and signal waveforms of various kinds of timing signals to drive a solid-state image pickup device can be easily changed according to specifications of apparatus using the solid-state image pickup device as an area image sensor.
Another object of the present invention is to provide a method of generating timing signals for driving a solid-state image pickup device, in which generating points of time and signal waveforms of various kinds of timing signals can be easily changed according to specifications of apparatus using the solid-state image pickup device as an area image sensor.
A further another object of the present invention is to provide an electronic apparatus which includes an electronic device to be driven by using timing signals of a plurality of kinds and which can generate the timing signals by using a relatively small amount of data.
According to one aspect of the present invention, there is provided a timing signal generating device for generating timing signals adapted for driving a solid-state image pickup device, wherein the image pickup device has a large number of photoelectric converter elements arranged in a row and column matrix and is capable of generating and outputting image signals for one frame in a plurality of horizontal scan periods, the image signals being generated and outputted within one horizontal scan period represent signal charges accumulated in the photoelectric converter elements of at least one row, the image pickup device has at least one operation mode, a plurality of operations is done in every said operation mode, the timing signal generating device comprising: at least one rewritable storage formed on a semiconductor substrate, for rewritably storing data; and a timing signal generator integrated together with said storage on the semiconductor substrate for receiving clock pulses, counting number of the clock pulses and generating, according to the data stored in said storage, a sequence of timing signals of a plurality of kinds for every operation mode of the solid-state image pickup device.
According to another aspect of the present invention, there is provided a method of generating timing signals adapted for driving a solid-state image pickup device, wherein the image pickup device has a large number of photoelectric converter elements arranged in a row and column matrix and is capable of generating and outputting image signals for one frame in a plurality of horizontal scan periods, the image signals being generated and outputted within one horizontal scan period represent signal charges accumulated in the photoelectric converter elements of at least one row, the image pickup device has at least one operation mode, a plurality of operations is done in every said operation mode, the method of generating timing signals comprising steps of; storing data necessary to generate the timing signals in at leas one rewritable storage formed on a semiconductor substrate, for rewritably storing data; and processing the data stored in said storage and generating a sequence of timing signals of a plurality of kinds for every operation mode of the solid-state image pickup device by using a timing signal generator integrated together with said storage on the semiconductor substrate, said timing signal generator receiving clock pulses and counting number of the clock pulses for detecting timing.
According to still another aspect of the present invention, there is provided an electronic apparatus, comprising; an electronic device driven by using (i) a plurality of kinds of first timing signals each of which is generated with a fixed repetition period and has a constant pulse waveform in every repetition period and (ii) a plurality of kinds of second timing signals each of which is generated in said repetition periods and in each of which the pulse waveform or number of pulses in said repetition period is not fixed, the generation of said first and second timing signals in every said repetition period is defined by signal generation control data, the electronic device has at least one operation mode, a plurality of operations is done in every said operation mode; and a timing signal generating device for generating said first and second timing signals adapted for driving said electronic device, wherein said signal generation control data includes at least one record for every operation mode of said electronic device, every said record includes a first field in which a control code for controlling one of the operations is recorded, a second field in which a code indicating one or more numerals representing one repetition period or successive repetition periods, said operation is executed once in every said repetition period, is recorded, and a third field in which a start address in said at least one rewritable storage, first record of a data defining the operation to be controlled by said control code being recorded at said start address, is recorded.
In the configuration of the timing signal generating device including at least one rewritable storage and a timing signal generator, the generating points of time, the signal waveforms, and the like of various kinds of timing signals to be generated by the timing signal generating device can be easily changed only by rewriting, by an external controller, timing signal generating data stored in the storage. Change in hardware of the timing signal generating device is not necessarily required.
The generating points of time and the signal waveforms of various kinds of timing signals adapted for driving a solid-state image pickup device can be easily changed according to specifications of apparatus using the solid-state image pickup device.
The signal generation control data for controlling generation of a timing signal includes an iteration count code as above, and hence the amount of data for control signal generation can be reduced. In an electronic apparatus including an electronic device to be driven by using timing signals of a plurality of kinds, the timing signals can be generated by using a relatively small amount of data.